Recently, there has been known a tablet printing apparatus that uses an inkjet print head for printing identification information such as characters, letters, marks or the like on tablets. In the tablet printing apparatus, tablets are conveyed by a conveyor belt. Ink is ejected from a nozzle of the inkjet print head located above the conveyor belt toward each tablet passing under the print head to print identification information on the tablet. The conveyor belt is wrapped around, for example, a drive pulley and a driven pulley, and is driven by the rotation of the drive pulley and the driven pulley.
Generally, on the occasion of maintenance such as cleaning and replacement of the conveyor belt, the conveyor belt is once removed from the apparatus and attached back to the apparatus after completion of the maintenance. At this time, in order to prevent degradation of the print quality on tablets, the conveyor belt needs to be attached to a predetermined position. However, it is difficult to attach the removed conveyor belt to the same position with high accuracy (for example, with an accuracy of 1 mm or less), and the conveyor belt may be displaced so as to be inclined with respect to the (regular) conveying direction of tablets in a horizontal plane. When such a displacement of the conveyor belt occurs, the tablet passing under the print head deviates from its desired position. As a result, the print quality tends to degrade.